JPH0229382A - Thermal sensitive recording sheet - Google Patents

Abstract

PURPOSE:To improve coloring sensitivity, the stability of colored part and noncolored part by employing substituted or unsubstituted phenacyl ether compound or substituted or unsubstituted phenacyl sulfide compound as a sensitizer CONSTITUTION:In a thermal sensitive recording sheet which contains a coating film containing coloring lacton compound, acid substance and sensitizer, phenacyl derivative represented by a general formula (I) or (II) is used, for example, as substituted or unsubstituted phenacyl ether compound or substituted or unsubstituted phenacyl sulfide compound used as the sensitizer. Acid substance normally has 10-1000 pts. per 100 pts.wt. of coloring lacton compound, the sensitizer is normally 1-1000 pts. per 100 pts. of the acid substance, the sheet base material is so coated drying weight of the coating solution of the substance 2-12g per 1m<2> of the material, and then dried at ambient temperature to approx. 50 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a heat-sensitive recording sheet that has extremely high color development sensitivity and excellent stability in color development areas and non-color development areas.

(Prior Art) A thermosensitive recording sheet is one that uses thermal energy to express images such as characters and figures on the recording sheet. It came to be used in fields such as bells and automatic ticket gates. There are various heat-sensitive recording methods, but from the viewpoint of image clarity, decomposition power, image tone, etc., we use a dye precursor, such as a color-forming lactone compound such as crystal violet lactone (CVL), and a color-developing lactone compound. The main method is to use acidic substances.

In this method, a phenolic compound such as bisphenol A, which is solid at room temperature but melts and liquefies upon heating and acts as an acid component, is conventionally used as an acidic substance.

At this time, as a heat-sensitive recording sheet, it must have a high degree of whiteness,
It is also required that the color developing area and non-coloring area be excellent in stability. And usually, rounding that produces vivid color is 14
It is necessary to maintain the temperature at about 0 to 150°C for a certain amount of time. Therefore, various approaches have been widely researched and reported in order to develop colors quickly and easily and vividly. For example, a method of adding stearic acid amide etc. as a sensitizer (JP-A-54-139740), a method of using benzyl p-hydroxybenzoate etc. as an acidic substance (JP-A-54-74762), etc. be.

(Problems to be Solved by the Invention) However, although the methods described in these publications improve color development sensitivity, they are still insufficient, and are also not satisfactory in terms of stability of color development areas and non-color development areas. It wasn't something.

(Means for Solving the Problems) In view of the above circumstances, the present inventors have conducted various studies and found that a substituted or unsubstituted phenacyl ether compound or a substituted or unsubstituted phenacyl sulfide compound is used as a sensitizer. It has been discovered that when used, a heat-sensitive recording sheet can be obtained which has a significantly higher effect of improving color development sensitivity than conventional sensitizers, and also has excellent stability in color development areas and non-color development areas, and has completed the present invention. Ta.

That is, the present invention provides a heat-sensitive recording sheet having a coating film containing a color-forming lactone compound, an acidic substance, and a sensitizer, in which the sensitizer is a substituted or unsubstituted phenacyl ether compound, or a substituted or unsubstituted phenacyl ether compound. The present invention provides a heat-sensitive recording sheet characterized by being made of a heptadyl sulfide compound.

As the substituted or unsubstituted phenacyl ether compound or the substituted or unsubstituted heptadyl sulfide compound used as a sensitizer in the present invention, for example, the following general formula (i) is used.
Alternatively, phenacyl derivatives represented by (ID) can be mentioned.

(In the formula, Xl, X2 are oxygen atoms or sulfur atoms, Y1
Y2 represents a hydrogen atom, a heron atom, an alkyl group, an aryl group, an alkyloxy group, an acyl group, a hydroxyl group, or a nitro group. In addition, tJ, R5, and R4 are hydrogen atoms,
Halodan atom or alkyl group, R is an aryl group, aralkyl group, phenacyl group, cycloalkyl group, acyl group, furfuryl group, or pyridyl group, 14 is a phenylene group, alkylene group, xylylene group, or ether bond, sulfide bond, or ester Indicates an alkylene group containing a bond in the chain. However, the aryl group, aralkyl group, phenacyl group, cycloalkyl group, phenylene group, alkylene group, and xylylene group include those substituted with substituents. Further, rs and m represent integers of 1 to 5. ) When y1 and y2 are an aryl group and R5 is an aryl group, an aralkyl group, a phenacyl group or a cycloalkyl group, examples of the substituent include a 710 G atom, a nitro group, an alkyl group, an alkenyl group, an aralkyl group, an aryl group. group, alkyloxy group, aralkyloxy group, aryloxy group, acyl group, acyloxy group, alkyloxycarbonyl group, alkyloxycarbonyl group, alkyloxycarbonyl group, acylalkyloxy group,
Examples of the substituent when R6 is a phenylene group, an alkylene group, or a xylylene group include a halodane atom, an alkyl group, an alkyloxy group, and an acyl group.

When y1 and y2 are aryl groups, and specific examples of R5, unsubstituted aryl groups such as phenyl, α-naphthyl, and β-su7thyl; chlorophenyl, dichlorophenyl, trichlorophenyl, pentachlorophenyl, bromophenyl, and cyfromo phenyl;
6-di-1ari-butylphenyl, 4-ethyl-2,6
-dit@rt-butylphenyl%4-fropenyl-2-
Methoxyphenyl, 4-71J Roux 2-methoxyphenyl, benzylphenyl, cumylphenyl, biphenyl, methoxyphenyl, ethoxyphenyl, benzyloxyphenyl, phenoxyphenyl, acetylphenyl, 2-benzoyl-5-methoxyphenyl, 2-pensoyl-5- Octyloxyphenyl, 2-benzoyl-
5-dodecyloxyphenyl, acetyloxyphenyl, benzoyloxyphenyl, methoxycardanylphenyl, ethoxycardanylphenyl, glopoxycardanylphenyl, impropoxycarbonylphenyl, butoxycargenylphenyl, imptoxycargenylphenyl, isoamide Roxycargenylphenyl, penzoloxycargenylphenyl, phenoxycargenylphenyl sp -tert-butylphenoxycarbonylphenyl, ID -t@rt-octylcarbonylphenyl, pentylmethoxyphenyl, penzoylmethoxytolyl, benzoyl Methoxyxylyl, pentylmethoxy(chlorophenyl), (pendiylmethoxycumyl)phenyl, benzoylmethoxy(benzoylphenyl Ltd)'roxyphenyl, hydroxytolyl, hydroxyxylyl, hydroxychlorophenyl, hydroxycumylphenyl, benzoyl(hydroxyphenyl) ); unsubstituted aralkyl groups such as pencil, 7enethyl, naphthylmethyl; 0-chlorobenzyl, m-chlorobenzyl, p-/lolobenzyl, bromobenzyl, methylbenzyl, tart-butylbenzyl, isoderpia A. Substituted aralkyl groups such as benzyl, α, α-dimethylbenzyl, α-7enylpencil, methoxybenzyl, phenoxybenzyl; phenacyl group; clotetraphenacyl, bromophenacyl, iodophenacyl, methylphenacyl, phenylphenacil, methoxyphenacil, nitro Substituted phenacyl groups such as phenacyl; substituted or unsubstituted cycloalkyl groups such as cyclohexyl and methylcyclohexyl; 'acyl groups such as J benzoyl, chlorobenzoyl, methylbenzoyl and naphthoyl; furfuryl group; Specific examples include unsubstituted phenylene groups such as 0-phenylene, m-phenylene, p-phenylene; 3-methyl-〇-phenylene, 4-methyl-〇-, phenylene, 2-methyl-〇-
Phenylene, 2-methyl-p-phenylene, 4-ri-alometaphenylene, 2-chloro-p-78nylene, 4-
Substituted phenylene groups such as pensoyl-m-phenylene; unsubstituted alkylene groups such as methylene, ethylene, propylene, ethylene, hexylene; substituted alkylene groups such as chloroethylene, chloropropylene, trimethylpropylene; 0
-xylylene group, m-xylylene group, p-xylylene group, 3-oxaintyrene, 3,6-thioxaoctylene, 3-thiobenthrene, 3,5-dioxa-2,
Examples include alkylene groups containing an ether bond, sulfide bond, or ester bond in the chain, such as 6-noon-octylene.

Furthermore, examples of the phenacyl component include unsubstituted phenacyl groups and substituted phenacyl groups such as hydrochlorophenacyl, bromophenacyl, iodophenacyl, methyl 7-enacyl, phenyl phenacyl, methoxy 7-enacyl, and nitrophenacyl.

Among these substituted or unsubstituted phenacyl ether compounds or substituted or unsubstituted heptadyl sulfide compounds, those with a melting point of 60 to 180°C are superior in coloring sensitivity upon heating and stability of coloring and non-coloring areas. is preferred.

Specific examples thereof include phenacyl derivatives (1) to (103) below.

(1) β-naphthylphenacyl ether, (2)
α-naphthylphenacyl ether, (3) phenyl phenacyl ether, (4) (o-chlorophenyl)
Phenacyl ether.

(5) (m-/lorophenyl) phenacyl ether, (6) (p-chlorophenyl) phenacyl ether, (7) (2,4-silolophenyl)7enacyl ether, (8) (2,4,6 -triclo is phenyl) phenacyl ether, αQ a (to) (IQ α force) (to) Co-bromophenyl) phenacyl ether, (m-bromophenyl) phenacyl ether, (p-20 mophenyl) phenacyl ether Nasyl ether, (214-dibromophenyl) phenacyl ether, (2,4,6-tribromophenyl) 7-enacyl ether, o-)ruyl 7-enacyl ether, (pt.rt-butylphenyl) phenacyl ether, (pt.rt-octylphenyl) phenacyl ether.

(2-methoxy-4-allyl-phenyl) phenacyl ether, (p-pensylphenyl) phenacyl ether, (p-α-cumylphenyl) phenacyl ether (c) (c) (to) (b) (to) 4 ( to) monotyl, 0-piphenylphenacyl ether, m-piphenylphenacyl ether, p-biphenyl 7-enacyl ether, (o-methoxyphenyl)phenacyl ether, (p-methoxyphenyl)phenacyl ether, (o -ethoxyphenyl) phenacyl ether, CP-benzyloxyphenyl) phenacyl ether, (p-phenoxyphenyl) phenacyl ether, (m-methylcarbonylphenyl) phenacyl ether, <p-methylcarzanylphenyl) phenacyl ether, C2-beacyl-5-methoxyphenyl) phenacyl ether, 01) (2-benzoyl-5-octyloxyphenyl) phenacyl ether, C(J(3-acetoxyphenyl) phenacyl ether, (to) (3-benzoyloxy phenyl) phenacyl ether, (n (4-methoxycarbonyl phenyl) phenacyl ether, (b) (4-ethoxycarbonylphenyl) phenacyl ether, HC4-n-f lopoxycarp nylphenyl) phenacyl ether, @ (4- inglopoxycarbonylphenyl) phenacyl ether, (b) (4-n-butoxycarbonylphenyl) phenacyl ether, OI (4-isotethoxycargenylphenyl) phenacyl ether.

-(4-penzyloxycarpnylphenyl)phenacyl ether, @I(4-phenoxycargenylphenyl)phenacyl ether, (6) Catechol di-7enacyl ether, resorcinol zophenacyl ether, ■ Hydroquinone diphenacyl ether , U (4-benzoylresorcin)
Zophenacyl ether, -catechol monophenacyl ether, strawberry resorcinol monophenacyl ether, (9) hydroquinone monophenacyl ether, M (4-benzoylresorcin) monophenacyl ether, <4 (o-nitrophenyl) phenacyl ether , (51) (p-nitrophenyl) phenacyl ether (1) phenyl (4-phenylphenacyl) ether, (e) 4-phenoxyphenyl (4-phenylphenacyl) ether, (54) phenyl (4-chloro phenacyl) ether, (55) 4-pencyloxyphenyl (4-chlorophenacyl) ether, (56) m-)lyl (4-bromophenacyl) ether, (57) (p-benzylphenyl)-4-bromophene Nasyl ether, (58) p-biphenyl (4-methyl 7-enacyl)
Ether, (59) β-naphthyl (4-methylphenacyl) ether, (60) 3.5-xylyl (4-nitrophenacyl) ether, (81) 2.5-xylyl (4-nitrophenacyl) ether , (62) p-biphenyl (3-methoxyphenacil) ether, (63) phenyl (4-7' romophenacyl) sulfide, (64) phenyl (4-phenylphenacyl) sulfide, (65) 2-su7 Tylphenacyl sulfide, (f
fs) 2-naphthyl (4-methylphenacyl) sulfide, (67) 4-/lorophenyl phenacyl sulfide, (
6B) 2-10 lophenyl (4-chlorophenacyl) sulfide, (69) 4-bromophenylphenacyl sulfide, (70) 4-methylphenyl (4-chlorophenacyl) sulfide, (71) 2-methylphenyl ( 4-phenylphenacyl) sulfide, (72) 4-t・rt-butylphenyl (4-nitrophenacyl) sulfide, (73) 4-methoxyphenyl (4-bromophenacyl) sulfide P1 (74) 2-hydroxyphenylphena Silsulfide, (75) 4-hydroxyphenylphenacylsulfide 7
(76) 4-hydroxyphenyl (4-methylphenacyl) sulfide, (77) 4-nitrophenylphenacyl sulfide, (7B) 2-nitrophenylphenacyl sulfide.

(79) Benzyl phenacyl sulfide, (80)
4-Methylpensylphenacyl sulfide, (81
) 4-chlorobenzylphenacyl sulfide, (8
2) Cyclohexyl (4-nitrophenacyl) sulfide, (IKI) furfuryl phenacyl sulfide, (8
4) Furfuryl (4-nitrophenacyl) sulfide, (85) 2-pyridyl (4-nitrophenacyl) sulfide, (86) 4-pyridylphenacyl sulfide, (8
7) Nophenacil sulfide, (8B) Bis(4-chlorophenacyl) sulfide, (89) Bis(4-bromophenacyl) sulfide, (90) 1,2-ethylenediphenacyl sulfide, (91) Bis( 2-(4-phenylphenacylthio)ethyl]ether, (92) 1,2-phenylene diphenacyl sulfide,
(93) 1,4-phenylene diphenacyl sulfide, (94) 4-methyl-1,2-7enylene diphenacyl sulfide, (95) p-xylylene diphenacyl sulfide,
(96) Ethylene glycol-bis÷4-chlorophenacylthioacetic acid) ester, (97) Ethylene glycol-bis(4-bromophenacylthioacetic acid) ester, (9B) Phenacylbenzoyl sulfide, (99
) Phenacyl=1-naphthoyl sulfide, (10
0) Phenacyl = 2-naphthoyl sulfide, (101
) Phenacyl (4-methylbenzoyl) sulfide.

(102) Phenacyl (4-chlorobenzoyl) sulfide, (103) Phenacyl (4-hydroxybenzoyl) sulfide.

Among them, (+), (4) t (s) * (11
) t (20) p(22) , (23) p (
25) −(28) v (29) −(30) −
(33) , (34) , (35) e (
39) t (40) , (43)'.

(45) , (46) , (50) , (
51) # (52), (53).

(55) t (56) e (57) t
(58) −(62) e (65) e(6
6), (67), (69), (70), (71), (7
3) #(75) , (76) , (77
) , (79) , (so) p (
si).

(82) , (84) t (85) e
(8B) - (89), (90).

(93), (94), (95), (96)
, (97) and (98) are preferred, and phenacyl derivatives having a melting point of 85 to 120°C are particularly preferred. Specific examples include (4), (it
) e (22) e (so) e(52) , (
55)? (57) # (65)? (70)
t (,7n'? (80) , (81) , (8
9), (95) <2) phenacyl derivatives.

Examples of the color-forming lacty compounds used in the present invention include t
t-f3. a-bis(p-dimethylaminophenyl) 7
Talide, 3,3-bis(p-dimethylaminophenyl)
-6-dimethylaminophthalide (also known as crystal violet lactone = = CVL), 3,3-bis(
p-dimethylaminophenyl)-6-amino 7thalip,
3.3-bis(p-dimethylaminophenyl)-6-
Nitrophthalide, 3,3-bis(p-dimethylaminophenyl)phthalide, 3,3-bis3-dimethylano-7-methylfluorane, 3-dinithylamino-7-p
Lofuran, 3-diethylamino-6-chloro-7-methylfluorane.

3-diethylamino-twoanilinofluorane, 3-diethylamino-6-methyl-7-7nilinofluorane,
3-piperidino-6-methyl-7-anilinoflu sec-2, 3-(N-ethyl-p-)luidino)-7-(N-methylanilino)fluorane, 3-(N-ethyl-p-)
Louisono)-6-methyl-7-anilinofur 2
-N-ethyl-N-ynylamino-6-methyl-7
-A; Rifluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-7nylinofluorane,
Fluoranphthalides such as 3-N,N-diethylamino-7-0-chloroanilinofluorane; Lactams such as Rhodamine B lactam; 3-methylspiro-cinna7
) h;yin, 3-ethylspirodinaphthopyran, 3-
Examples include spiropyrans such as penjiruspi grass naphthopyran. Of course, these compounds must be colorless or light-colored and develop color when reacting with acidic substances.

Furthermore, the acidic substance used in the present invention is solid at room temperature;
Any compound may be used as long as it melts and liquefies when heated to about 60 to 180°C, opens the lactone ring of the color-forming lactone compound, and develops color, and any of them functions well in the presence of a sensitizer. Examples of these include 4-phenylphenol, 4-hydroxyacetophenone, 2,2'-dihydroxydiphenyl, 2,2'-methylenebis(4-chlorophenol), 2,2'-methylenebis(4-methyl −
6-butylphenol), 4#4'-ingropylidenediphenol (also known as bisfe,!-AL4t4'
-isoglopylidene bis(2-chlorophenol), 4
#4'-'f Nogropyridenobis(2-methylphenol), 4,4'-ethylenebis(2-methylphenol), 4,4'-thiobis(6-t-butyl-3-methylphenol Llrl -bis(4-hydroxyphenyl)
-Cyclohexane, 2.2'-bis(4-hydroxyphenyl)-n-hebutane, 4.4'-cyclohexylidenebis(2-isoglobylphenol), 4.4'-sulfonyldiphenol, salicylic acid anilide , novolac type phenol resin, benzyl p-hydroxybenzoate, and the like.

These acidic substances are usually used in an amount of 10 to 1,00 parts by weight per 100 parts by weight (hereinafter simply referred to as parts) of the color-forming lactone compound.
0 parts, preferably 100 to 500 parts of Vi are used.

The sensitizer is usually used in an amount of 1 to 1.00 parts per 100 parts of the acidic substance.
0 parts, preferably 30 to 100 parts are used.

The color-forming lactone compound, acidic substance, and sensitizer are all used in the form of fine particles, preferably fine particles having a particle size of several microns or less.

A variety of generally known methods can be used to produce heat-sensitive recording sheets, but the usual method is to prepare a coating solution in which a color-forming lactone compound, an acidic substance, and a sensitizer are dispersed in water or an organic solvent. The method for applying this to the sheet substrate is to prepare a coating liquid in which a color-forming lactone compound and an acidic substance are separately dispersed in water or an organic solvent, and at least one of them contains a sensitizer. , a method of laminating and coating these coating liquids on a sheet base material, etc. can be adopted. Of course, the above-mentioned coating liquid may contain binders such as polyvinyl alcohol, methylcellulose, hydroxyethylcellulose, calgeximethylcellulose, starches, styrene, etc.
- aqueous binders such as maleic acid copolymers, polyacrylics, polystyrenes, polyesters, polyolefins, polycarbonates, polyurethanes, polyvinyl chloride,
An oily binder such as polyvinyl acetate or the like must be added. In addition, in order to improve performance, the coating liquid may contain ultraviolet absorbers such as benzophenone and triazole, fillers such as calcium carbonate, lubricants such as polyethylene wax and paraffin wax, waterproofing agents, etc.
Various other agents can be added. Furthermore, various dispersants for dispersing various drugs in water can be added to the coating liquid.

The dry weight of the coating liquid is generally 2 to 1 on the sheet base material.
The heat-sensitive recording sheet of the present invention can be obtained by applying the composition to a sheet base material so as to have a film density of 2fi, and then drying it at room temperature to about 50°C.

Paper is generally used as the sheet base material, but synthetic resin sheets, nonwoven fabric sheets, etc. can also be used as appropriate.

(Examples) Next, the present invention will be explained in more detail with reference to Examples, Comparative Examples, and Test Examples, but the present invention is not limited thereto in any way. In addition, all parts and parts in one example are based on weight.

Example I Solution A (dye solution) 3-(N-ethyl-p-toluidino)-6-methyl-7
- Anilitus fluorane 1.0 parts (o-chloropher) phenacyl ether 2,0 parts 104 Polyvinyl alcohol aqueous solution 3.0 parts Total
11.・0 parts B liquid (acidic substance liquid) Bisphenol A 3.0 parts Calcium carbonate 3.0 parts Zinc stearate 0.5 parts 10cfb polyvinyl alcohol aqueous solution 7.0 parts Water
10.0 copies total
23.5 parts The above liquid and liquid B were separately blended and each was pulverized and dispersed with a paint conditioner to obtain a coating liquid stock solution.

Next, 11.0 parts of liquid A and 23.5 parts of liquid B were mixed to form a heat-sensitive coating liquid, which was coated on 64.517 nl of high-quality paper with a dry coating amount of 81/? The mixture was coated in the following manner and dried to obtain a heat-sensitive recording sheet of the present invention.

This sheet was excellent in color development sensitivity and stability of color development areas and non-color development areas.

Examples 2 to 53 The above (g, (s), (tg t (20) e (
22) *(23) , (25) , (28) ,
(29) , (30) , (33) j(34)
, (35) t (39) * (40) −(4
3) , (45) −(46) , (50)
* (51) or (52) t (53)
t (55) p (56) # (57) e
(58) , (62) , (65) , (66
).

(67) f (69)? (70), (71)
# (73)? (75) #(76) , (7
7) , (79) t (go) , (al) ,
(82).

(84), (85)? (88), (89)
, (90)? (93).

(94) , (95) p (96) # (97)
A heat-sensitive recording sheet of the present invention was obtained in the same manner as in Example 1 except that the phenacyl derivatives (98) and (98) were used.

All of these sheets were excellent in color development sensitivity and stability of color development areas and non-color development areas.

Example 54 The amount of 0-chlorophenylphenacyl ether added was 1.
A heat-sensitive recording sheet of the present invention was obtained in the same manner as in Example 1, except that the amount of liquid A was changed to 0 parts and the amount of liquid A used was 10 parts.

This sheet was excellent in color development sensitivity and stability of color development areas and non-color development areas.

Example 55 The amount of 0-chlorophenyl 7-enacyl ether added was 4.
A heat-sensitive recording sheet of the present invention was obtained in the same manner as in Example 1, except that the amount of liquid A was changed to 0 parts and the amount of liquid A used was 13 parts.

This sheet was excellent in color development sensitivity and stability of color development areas and non-color development areas.

Comparative Example 1 A heat-sensitive recording sheet for comparison was obtained in the same manner as in Example 1, except that the addition of 0-chlorophenyl 7-enacyl ether was omitted and the amount of liquid A used was 9.0 parts.

This sheet had poor color development sensitivity.

Comparative Example 2 A heat-sensitive recording sheet for comparison was obtained in the same manner as in Example 1 except that stearic acid amide was used as a substitute for o-10 lophenyl phenacyl ether.

This sheet was inferior in color development sensitivity and stability of color development areas and non-color development areas.

Comparative Example 3 Same as Example 1 except that the addition of o-chlorophenylphenacyl ether was omitted, the amount of liquid A used was 9 parts, and benzyl p-hydroxybenzoate was used instead of bisphenol. A heat-sensitive recording sheet for comparison was obtained.

This sheet was inferior in color development sensitivity and stability of color development areas.

Test Example 1 Tests regarding the color development sensitivity and stability of color development areas and non-color development areas of the thermal recording sheets obtained in Examples 1 to 55 and Comparative Examples 1 to 3 were conducted as follows.

The results are shown in Table-1.

[Evaluation of color development sensitivity]

Using an MgI type thermal head printing device manufactured by Matsushita Electronic Components Co., Ltd., printing is performed on the sheet under the conditions of a pulse width of 0.1 to 1.0 milliseconds, and the color is developed, and the color density is measured using a Macbeth density meter manufactured by Fukubeth Co., Ltd. The pulse width was measured using RD-918, and the pulse width when the color density value reached 1.0 was determined from the color density/Noculus width curve, and the color sensitivity was evaluated based on the magnitude of this pulse width value. () The smaller the value of the arm lux width, the higher the color development sensitivity. ).

[Evaluation of the stability of colored areas and non-colored areas] Using the sheets printed under the above conditions, the stability of colored areas and non-colored areas was evaluated under the following two conditions (conditions A and B). Ta.

(Condition A) The above sheet was left in an atmosphere with a temperature of 60°C and a humidity of 25%, and after 24 hours, the degree of whitening and decolorization of the colored area and background fogging of the non-colored area was visually checked according to the following criteria. evaluated.

1) Evaluation of colored areas ■ Evaluation criteria for whitening ◎: No whitening O: Almost no whitening Δ: Whitening) ×: Significant whitening ■ Evaluation criteria for decoloring O: No decoloring O: No decoloring None Δ: Discoloration ×: Significant discoloration 2) Evaluation of non-pigmented areas ■ Evaluation criteria for background fog O: No background capri 0: There is no background fog Δ: With background capri × : Significant background capri (condition B) The sheet was left in an atmosphere with a temperature of 40°C and a humidity of 90%, and after 24 hours, the degree of discoloration of the colored area was visually checked using the same base salt as in condition A. I evaluated it.

(Effects of the Invention) The heat-sensitive recording sheet of the present invention has extremely high color development sensitivity;
Moreover, it has the advantage of being excellent in stability of the coloring area and the non-coloring area.

Claims (1)

[Scope of Claims] 1. A heat-sensitive recording sheet having a coating film containing a color-forming lactone compound, an acidic substance, and a sensitizer, in which the sensitizer is a substituted or unsubstituted phenacyl ether compound, or a substituted or unsubstituted phenacyl ether compound. A heat-sensitive recording sheet characterized by being a substituted phenacyl sulfide compound. 2. The heat-sensitive recording sheet according to claim 1, wherein the sensitizer is a phenacyl ether compound or a phenacyl sulfide compound represented by the following general formula (I) or (II). ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(II) (In the formula, X^1, X^2 are oxygen atoms or sulfur atoms, Y^
1, Y^2 represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an alkyloxy group, an acyl group, a hydroxyl group, or a nitro group. Also, R^1, R^2, R^3
, R^4 is a hydrogen atom, a halogen atom or an alkyl group, R
^5 is an aryl group, aralkyl group, phenacyl group, cycloalkyl group, acyl group, furfuryl group, or pyridyl group, R^6 is a phenylene group, alkylene group, xylylene group, or an ether bond, sulfide bond, or ester bond in the chain Indicates the alkylene group contained in However, the aryl group, aralkyl group, phenacyl group, cycloalkyl group, phenylene group, alkylene group, and xylylene group include those substituted with substituents. Furthermore, n and m represent integers of 1 to 5. ) 3. The sensitizer is selected from the following phenacyl derivatives 1.
The heat-sensitive recording sheet according to claim 1, which is a compound of at least one species. β-naphthylphenacyl ether, (o-chlorophenyl)phenacyl ether, (2,4
,6-trichlorophenyl)phenacyl ether, (p-bromophenyl)phenacyl ether, o-biphenylphenacyl ether, p-biphenylphenacyl ether, (o-methoxyphenyl)phenacyl ether, (o-
(ethoxyphenyl) phenacyl ether, (m-methylcarbonylphenyl) phenacyl ether, (p-methylcarbonylphenyl) phenacyl ether, (2-benzoyl-5-methoxyphenyl) phenacyl ether, (3-benzoyloxyphenyl) Phenacyl ether, (4-ethoxycarbonylphenyl)phenacyl ether, (4-isobutoxycarbonylphenyl)phenacyl ether, (4-benzyloxycarbonylphenyl)phenacyl ether, resorcin diphenacyl ether, (4-benzoylresorcin) ) diphenacyl ether, catechol monophenacyl ether, (o-nitrophenyl) phenacyl ether, (p-nitrophenyl) phenacyl ether, phenyl (4-phenylphenacyl) ether, 4-phenoxyphenyl (4-phenyl) phenacyl) ether, 4-benzyloxyphenyl (4-chlorophenacyl)
Ether, m-tolyl (4-bromophenacyl) ether, (p-
benzylphenyl)-4-bromophenacyl ether, p-biphenyl (4-methylphenacyl) ether, p-biphenyl (3-methoxyphenacyl) ether, 2-naphthylphenacyl sulfide, 2-naphthyl (4-methylphenacil) sil) sulfide, 4-chlorophenylphenacyl sulfide, 4-bromophenylphenacyl sulfide, 4-methylphenyl (
4-chlorophenacyl) sulfide, 2-methylphenyl (4-phenylphenacyl) sulfide, 4-methoxyphenyl (4-bromophenacyl) sulfide, 4-hydroxyphenylphenacyl sulfide, 4-hydroxyphenyl (4-methylphenacyl) ) sulfide, 4-nitrophenyl fairyl sulfide, benzylphenacyl sulfide, 4-methylbenzylphenacyl sulfide, 4-chlorobenzylphenacyl sulfide, cyclohexyl (4-
nitrophenacyl) sulfide, furfuryl (4-nitrophenacyl) sulfide, 2-pyridyl (4-nitrophenacyl) sulfide, bis(4-chlorophenacyl) sulfide, bis(4-
bromophenacyl) sulfide, 1,2-ethylene diphenacyl sulfide, 1,4-phenylene diphenacyl sulfide, 4-methyl-1,2-phenylene diphenacyl sulfide, p-xylylene diphenacyl sulfide, ethylene glycol-bis ■4-chlorophenacylthioacetic acid) ester, ethylene glycol-bis■4-bromophenacylthioacetic acid) ester, phenacylbenzoyl sulfide. 4. The sensitizer is selected from the following phenacyl derivatives 1
The heat-sensitive recording sheet according to claim 1, which is a compound of at least one species. (o-chlorophenyl) phenacyl ether, (p-bromophenyl) phenacyl ether, p-biphenylphenacyl ether, (o-nitrophenyl) phenacyl ether, phenyl (4-phenylphenacyl) ether, 4-benzyloxy Phenyl (4-chlorophenacyl) ether, (p-benzylphenyl)-4-bromophenacyl ether, 2-naphthylphenacyl sulfide, 4-methylphenyl (4-chlorophenacyl) sulfide, 4-nitrophenyl phenacyl sulfide, 4-methylbenzylphenacyl sulfide, 4-chlorobenzylphenacyl sulfide, bis(4-bromophenacyl) sulfide, p-xylylene diphenacyl sulfide. 5. The heat-sensitive recording sheet according to claim 1, wherein the amount of the sensitizer in the coating film is 30 to 100 parts by weight per 100 parts by weight of the acidic substance.